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General Tech One Person Brake Bleeding with a Mityvac

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Richter12x2

Jedi Hopeful
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I changed out my rubber brake lines for new braided stainless ones on the Triumph GT6 yesterday, so today it was time to bleed them.

I spent about 30 minutes by the passenger rear wheel, pumping the mightyvac like crazy to keep suction in it, and getting nothing but a long stream of bubbles that never improved. I finally gave up and moved over to the other rear wheel, with the same results. This is pretty much what happened last time, where it finally ended up good enough to get it to a shop and pay someone about $100 to bleed the brakes with a pressure bleeder. Wasn't looking forward to that again, but I knew I at least had to finish the 4 wheels to get some sort of brake fluid back in there before I could even consider getting it down and over to the garage.

Forearms hurting from pumping, I took a break, and pulled up Google on my phone and searched "How to bleed brakes with a mightyvac" and got this video: https://www.youtube.com/watch?v=KTY2iBkFeV0

So I'm watching, and he gets to the part about taking the bleeder valve out and putting 4 loops of teflon tape on it and putting it back in, and I'm thinking "Okay, that's probably overengineering, it can't make that much difference, you're just going to be wasting brake fluid while you put the teflon tape on". So I went back to the passenger front wheel, pumped up the mightyvac and cracked the bleed nipple, and same story, bubbles like crazy and no signs of improvement. So I thought "Well, heck, I'll try it, and if the guys at the brake shop laugh that I have teflon tape on my brake nipples, so be it." Stuck a cup under the caliper and pulled the nipple out, wrapped it around 4 times with teflon tape, and threaded it back in. Topped up the master cylinder again, hooked the mightyvac back up and pumped it up to 20 again. Cracked the nipple and a solid wall of clean fluid came through, with just a few microscopic bubbles (which he explained are usually just from sucking air up the threads.)
More telling, now, from the initial pump up to -20, it only got to -15 before I had to top up the master cylinder. Before I would pump to -20, crack the nipple open and run it down to -5 about 7 times before I had to top up. (I counted, because I'm doing this in the garage and it's a pain to get out from between the wall and the car to check the fluid level, but I didn't want to run it dry either.)
After another 2 top ups, I was satisfied I had a totally negligible amount of air in the lines. This is probably the 10th time I've bled brakes on a car and the first time I can really, honestly say that I feel good that I'm sure I got it all, and it took about 5 minutes to do the corner, vs 30 minutes of flailing to no effect.
Re-did the other wheels, with the same result, every time. I went ahead and ran through the rest of the brake fluid on the rear wheels since it goes bad storing it, just to be sure that I got it all, but it was pretty obviously perfectly fine long before I wrapped up.
A quarter's worth of teflon tape, and a minute to pull the nipple and wrap it, to save $100, (or a life, potentially, from dodgy brakes). I'm definitely a believer now.


 
I've always used the MityWife method of bleeding brakes ("pump.. pump.. pump and hold...") :smile:

Scott
 
I have only vacuum bled once or twice. I don't have a real Mityvac, I have two generics. Both the generic tools mention using sealant on the bleed nipple threads. It does make a difference.

I have never used the pump, pump, pump and hold method to bleed brakes. I use a modified version of the 2-person flush method. I have a bleed hose with a check valve in it. I put grease (yes, grease) on the bleed nipple threads (instead of Teflon tape), connect my bleed hose, and crack the nipple one-half turn open. Then I top up the reservoir and SLOWLY push the brake pedal down while watching the bleed hose. I repeat the slow pedal depressions until I see no more bubbles coming out of the hose. The check valve and grease on the nipple threads allow me to do this work without the assistance of a helper. My "helpers" always seemed to get annoyed that I was using so much of their time.

An alternative to my custom bleed hose, the grease, or Teflon tape is to buy the correct size of Speed-Bleeders. Speed-Bleeders have built in check valves and a sealant on the threads.
 
HerronScott said:
I've always used the MityWife method of bleeding brakes ("pump.. pump.. pump and hold...") :smile:

Scott
Click to expand...

I've tried this method a couple of times, it works alright but it seems to cause some hard to eliminate whining and groaning that lasts long after the process is complete. :D
 
I had a similar experience bleeding my MGB. Exiting fluid looked like foam with the vacuum gizmo. Obviously air sneaking past the bleeder threads. I finished it off with the "pump,pump,hold" system and all was fine. As a side note the vendor of the "speedy-bleeders" also sells a thread sealant as the speedy-bleeders are only good for a few uses before they start to inhale air through the threads.
 
I've found that using the brake pedal to get fluid going into a container and then using a Mityvac to finish the job is a lot more time effective knowing first hand what the OP describes.
 
The nice thing was, it's actually kindof a combo method, because when you take the bleed nipple out to put the tape on, you're actually letting the brake fluid drain air out of the system as well, truth be told, by the time I hooked up the mighty-vac, most of the air was already out of the system just from using the 'gravity method' that I've heard some people swear by. I had clean solid wall of fluid on the first pump on all 4 corners. I gave a couple of pumps of the brake pedal before I started just because I ran the master cylinder dry accidentally while trying to get the brake lines on (one of the existing lines had some sketchy threads on it, so it took too long to straighten out, even with plastic wrap stuffed under the master cylinder cap.)
 
I've always had luck with a one way check valve (Ezee Bleed I think its called). Stock bleeder screws but I honestly can't recall if I have teflon tape on the threads of the bleed valve. I seem to think I do.

Bob
 
Richter12x2 said:
I've tried this method a couple of times, it works alright but it seems to cause some hard to eliminate whining and groaning that lasts long after the process is complete. :D
Click to expand...

So that's what was causing that? ;)

Scott
 
Another vote for speed bleeders. Never had much problem the conventional way but speed bleeders for $30 or so well worth it. One man job and no gizmo needed.
 
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